1. Field of the Invention
This invention relates to printing presses, to a web-fed printing press, and particularly to that having a plurality of printing units each having at least one plate cylinder capable of carrying a plurality of printing plates in preassigned longitudinal positions thereon. More particularly, the invention pertains to a system for controlling the making of a set of printing plates, as for each newspaper issue, and the subsequent mounting thereof to the preassigned positions on the plate cylinder or cylinders of each printing unit, with a view to making sure that the printing plates are all mounted in the correct positions.
2. Description of the Prior Art
A web-fed rotary printing press for newspaper production usually incorporates from three to ten paper supply units, as many printing units, and one folding unit. Paid off from their rolls in the supply units, the webs of paper are printed on both sides, in either monochrome or multiple colors, by the printing units, then superposed one upon another, and then cut and folded into signatures of multiple pages in the folding unit.
In today""s large newspaper production plants, moreover, several printing press systems, each composed of the noted combination of supply units and printing units and folding unit, are put to conjoint operation. Typically, each printing unit is of the well-known offset perfecting press design, having two plate cylinders and two blanket cylinders for concurrently printing both sides of the web. Each such printing unit of each press system permits the mounting, at one time, of up to as many as sixteen so-called xe2x80x9cbroad sizexe2x80x9d printing plates. A formidably large number of printing plates are thus employed for production of each newspaper issue. All such printing plates must of course be mounted in the correct positions on the correct plate cylinders.
The trouble is that human labor is yet relied upon for mounting such huge numbers of printing plates to the plate cylinders. The human labor grows heavier, furthermore, as news are updated hour by hour, minute by minute, even during the progress of newspaper production, demanding the mounting of new printing plates for each latest edition. Even greater numbers of printing plates are required as the newspaper contents usually differ for different areas of distribution. Actually, substantive wastes of paper have frequently occurred as a result of the mounting of printing plates in wrong positions on the plate cylinders or even to wrong plate cylinders.
Attempts have indeed been made to eliminate such mounting errors, a typical one, perhaps closest to the instant invention, being found in Japanese Unexamined Patent Publication No. 10-202840. It teaches to print on each printing plate information as to which plate cylinder, and which position thereon, the plate is to be mounted to. The information is supplied to the printer from a memory on which there is stored all the data necessarily for mounting the complete set of printing plates in the required positions on the required plate cylinders. After the printing plates have been manually mounted, the printings thereon are read and compared with the data stored on the memory.
An objection to this prior art system is that there is printed on the printing plates only the information on the plate cylinders and the positions thereon to which they are to be mounted, with no indication whatsoever as to their contents, that is, the matter to be printed by the plates. It is therefore not clear how the contents of the printing plates are recognized in mounting them to the plate cylinders. The workers must be uncertain whether they are mounting the correct printing plates in the correct positions.
It is not disclosed, either, how the system knows the positions on the plate cylinders in which the printing plates have actually been mounted. A comparison of the readings of the printings on the mounted printing plates with the data stored on the memory provides no firsthand knowledge of whether they are on the correct plate cylinders, and in the correct positions thereon, or not.
An additional objection concerns use of a charge-coupled-device camera for reading the printings on the printing plates. The CCD camera together with associated electronics made the prior art system very expensive. It is mentioned that the CCD camera is replaceable by a barcode reader, but no actual construction is shown in support of this alternative. A barcode reader, moreover, as used in this prior art system in place of the CCD camera, does not resolve the ambiguity pointed out above.
The same unexamined Japanese patent publication also suggests to print on the printing plates barcoded information indicative of which plate cylinder, and which position thereon, each plate is to be mounted to. On being read by a barcode reader, the information is printed again, this time in visually recognizable form, on each printing plate using an ink that does not affect printing. The workers are supposed to mount the printing plates in the required positions on the required plate cylinders by visually observing the printings thereon. After the printing plates are thus mounted, the printings thereon are read by a CCD camera for comparison with the information that has been read by the barcode reader before the plates are mounted.
The twofold reading of the printings on the printing plates necessarily makes reading errors twice as probable as in the case of one reading only. Despite the complex confirmation processes involved, this second prior art method is even more unreliable than the first.
The second prior art method is also akin to the first in failing to teach how the system knows the positions on the plate cylinders in which the printing plates are mounted. A comparison of the barcode readings before the printing plates are mounted and the CCD camera readings after they are mounted is not enough to determine whether each plate is in the correct mounting position or not.
The present invention seeks to thoroughly defeat the shortcomings and ambiguities of the prior art by providing an improved, totally practicable plate-making and -mounting control system capable of accurately pinpointing any printing plates that are mounted in wrong plate-making positions on any plate cylinders of any printing units.
Another object of the invention is to expedite the manual mounting of printing plates to plate cylinders by providing on the printing plates the printings that are readily recognizable by the workers besides being machine readable, enabling them to visually confirm the required plate-mounting position on the required plate cylinder as they handle each printing plate.
Yet another object of the invention is to reduce the probability of reading errors to a minimum by providing a plate-making and -mounting control system that requires reading of the printings on the printing plates at one time only.
Briefly, the present invention may be summarized as a platemaking and -mounting control system in a rotary printing press for production of multiple-page printings, the press being of the type having at least one plate cylinder with a plurality of predefined plate-mounting positions for having as many printing plates mounted thereto, and a plate maker for making a set of printing plates to be mounted to the preassigned plate-mounting positions on the plate cylinder.
The plate-making and -mounting control system according to the invention comprises an assignment controller which provides, in response to the inputting of a required set of directions for each specific printing job, ASSIGNMENT INFO indicative of how a set of printing plates to be made for the job are assigned to the plate-mounting positions on the plate cylinder. A plate-maker controller is provided for controlling the plate maker making the set of printing plates and for providing CONTENTS INFO indicative of the matter to be printed by each printing plate being made by the plate maker. In response to the ASSIGNMENT INFO from the assignment controller and the CONTENTS INFO from the plate-maker controller, a printer controller provides POSITION INFO indicative of a desired plate-mounting position on the plate cylinder to which each printing plate being made by the plate maker is to be mounted. A printer, under the control of the printer controller, prints the POSITION INFO on each printing plate that has been made by the plate maker.
After the mounting, perhaps by human labor, of the complete set of printing plates to the plate cylinder, the POSITION INFO printings on the printing plates are read by reader means, which thereupon put out the POSITION INFO read from each printing plate, together with READER INFO indicative of the actual plate-mounting position on the plate cylinder in which that printing plate is mounted. Whether each printing plate is mounted to a correct plate-mounting position on the plate cylinder or not is subsequently determined, by control electronics familiar to the specialists, on the bases of both POSITION INFO and READER INFO fed from the reader means.
Thus, as a first advantage gained by the plate-making and -mounting control system summarized above, the POSITION INFO printed on each printing plate is derived from both ASSIGNMENT INFO from the assignment controller and CONTENTS INFO from the plate-maker controller. The POSITION INFO will therefore indicate the desired plate-mounting position on the plate cylinder for each printing plate in exact agreement with the matter to be printed by that printing plate.
Preferably, as in the typical embodiment of the invention to be disclosed subsequently, the printer may be disposed immediately downstream of the plate maker in order to print the POSITION INFO on each printing plate that has just issued therefrom. There can thus be eliminated the risk of the POSITION INFO being printed on wrong printing plates.
Another pronounced advantage of the invention is that, on reading the POSITION INFO printing on each printing plate on the plate cylinder, the reader means put out the POSITION INFO reading together with the READER INFO uniquely identifying the particular plate-mounting position on the particular plate cylinder in which that printing plate is mounted. In short the output from the reader means tells which plate-mounting position on which plate cylinder the printing plate from which the POSITION INFO has been recovered is mounted in. The POSITION INFO reading in combination with the READER INFO makes it possible to infallibly determine whether each printing plate is mounted in the correct plate-mounting position on the correct plate cylinder or not.
It will also be appreciated that the printings on the printing plate are read only once according to the invention. The probability of reading errors is thus minimized.
According to an additional feature of the invention, the POSITION INFO printings on the printing plates are provided both in machine decipherable form, such as barcode, and in human discernible form, such as letters and numerals. The human discernible printings are intended to facilitate the manual mounting of the printing plates. The barcode printings are preferred because of the simplicity and inexpensiveness of the facilities required for reading.
The above and other objects, features and advantages of this invention will become more apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference had to the attached drawings showing a preferred embodiment of the invention.